Achillobator - how big is it??

["Timothy Williams" <twilliams_alpha@hotmail.com>]

I just finished reading the description of _Achillobator_ by Perle, Norell 
and Clark (1999).  The paper is a little (ahem) unpolished (for the reasons 
given in an earlier post).

Anyway, there is one thing I still can't work out, even after reading the 
paper.  How BIG is _Achillobator_?  The authors state it is three times the 
size of _Deinonychus_, which should put it in the ball-park of 8 to 9m.

The femur of _Achillobator_ is about 50cm long.  As a ROUGH guide to the 
size of smaller dromaeosaurids, the total adult body length is about ten 
times the femoral length: _Deinonychus_'s femur is about 30cm, 
_Velociraptor_'s is about 20cm.  This doesn't hold for bigger dromies - I'm 
guessing their legs are proportionately shorter (i.e. compared to total body 
length) than their smaller cousins.  This must be especially true for 
_Achillobator_.  So can anyone tell me how big _Achillobator_ might have 
been, and how you worked it out?

Another thing I thought was interesting concerns the sickle-like ungual of 
the second toe (the "killer claw").  _Achillobator_ has the typical dromie 
morphology of the second toe (especially the claw-bearing phalanx).  But 
based on the figures, _Achillobator_'s "killer-claw" isn't really all that 
big.  It's only around 11cm long (that's linear length, not around the curve 
of the claw).  It's only a little bigger than the killer claw of a 2.8m-long 
_Deinonychus_ (ungual 9-10cm long), and much smaller than _Utahraptor_'s 
(c.6m long) killer claw (around 20cm).

_Adasaurus_ has only a small killer claw (by dromie standards), but I'm not 
sure the specimen is adult, or even a dromaeosaurid.  (As for _Hulsanpes_, 
it is definitely is NOT a dromie.)


Tim
______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com